feat: migrate chat orchestration to deep langgraph workers

app/main.py

@@ -18,9 +18,8 @@ from app.config.settings import settings
 
 @asynccontextmanager
 async def lifespan(app: FastAPI):
-    # Startup: initialise DB connection pool and agent registry
-    from app.core.agent_registry import registry  # noqa: F401 — triggers module load
-    import app.agents  # noqa: F401 — triggers @registry.register decorators
+    # Startup: ensure agent tool modules are loaded.
+    import app.agents  # noqa: F401
 
     yield
 
@@ -51,11 +50,10 @@ def create_app() -> FastAPI:
     app.add_middleware(SanitizerMiddleware)
     app.add_middleware(TierRateLimitMiddleware)
 
-    from app.api.routes import agent_setup, agents, auth, backup, billing, chat, device_ws, plans, plugins, storage, vectors
+    from app.api.routes import agent_setup, agents, auth, backup, billing, chat, device_ws, plugins, storage, vectors
 
     app.include_router(auth.router,       prefix="/api/v1")
     app.include_router(chat.router,       prefix="/api/v1")
-    app.include_router(plans.router,      prefix="/api/v1")
     app.include_router(storage.router,    prefix="/api/v1")
     app.include_router(vectors.router,    prefix="/api/v1")
     app.include_router(backup.router,     prefix="/api/v1")